Abstract: A downhole tool that comprises an outer housing with an uphole end, a downhole end and an inner surface therebetween. The inner surface defines an interior space with a first inner-diameter and a recess with a larger second inner-diameter. The downhole tool also comprises a sleeve that is positionable within the recess of the outer housing. The sleeve comprises a ramp with a larger inner diameter towards an uphole end. The tool also comprises a seat that is positionable within the sleeve. The seat defines at least one plateau section that is configured to receive and support an equatorial portion of a ball, wherein when a pressure force is applied to the ball and seat, the ball and the seat slide along the ramp and a compressive force is applied to the equatorial portion of the ball.

Abstract: A wellbore assembly including an actuation dart for actuating a target tool in tubing string. The dart is activatable downhole, such that it can be moved past tools similar to the target tool without actuating them. The target tool may include a release mechanism that releases the actuation dart after being actuate by it. Such a target tool may be useful with a second tool that retains the actuation dart against further movement down the tubing string.

Abstract: A downhole tool that comprises an outer housing with an uphole end, a downhole end and an inner surface therebetween. The inner surface defines an interior space with a first inner-diameter and a recess with a larger second inner-diameter. The downhole tool also comprises a sleeve that is positionable within the recess of the outer housing. The sleeve comprises a ramp with a larger inner diameter towards an uphole end. The tool also comprises a seat that is positionable within the sleeve. The seat defines at least one plateau section that is configured to receive and support an equatorial portion of a ball, wherein when a pressure force is applied to the ball and seat, the ball and the seat slide along the ramp and a compressive force is applied to the equatorial portion of the ball.

Abstract: A wellbore assembly including an actuation dart for actuating a target tool in tubing string. The dart is activatable downhole, such that it can be moved past tools similar to the target tool without actuating them. The target tool may include a release mechanism that releases the actuation dart after being actuate by it. Such a target tool may be useful with a second tool that retains the actuation dart against further movement down the tubing string.